sedimentary
Flint / Chert
Silicon Dioxide (SiO2)
Hardness of 7 on the Mohs scale, typically dark gray, black, or brown with a waxy to vitreous luster, conchoidal fracture, and no cleavage.
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Physical properties
Hardness of 7 on the Mohs scale, typically dark gray, black, or brown with a waxy to vitreous luster, conchoidal fracture, and no cleavage.
Formation & geological history
Formed through the chemical replacement of limestone or chalk by silica-rich solutions in marine environments during the Cretaceous and other periods.
Uses & applications
Historically used for making stone tools, weapons, and fire-striking; currently used in abrasives and decorative gravel.
Geological facts
Flint is a variety of chert that occurs specifically in chalk or marly limestone. It produces sharp edges when fractured, making it ideal for ancient tools.
Field identification & locations
Easily identified by its conchoidal fracture and hardness that scratches glass; commonly found in gravel deposits, chalk cliffs, and riverbeds.
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